Hi Paul, On Mon, Aug 31, 2020 at 11:14:15AM -0700, paulmck@xxxxxxxxxx wrote: > From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> > > This commit adds a destination CPU to __call_single_data, and is inspired > by an earlier commit by Peter Zijlstra. This version adds #ifdef to > permit use by 32-bit systems and supplying the destination CPU for all > smp_call_function*() requests, not just smp_call_function_single(). > > If need be, 32-bit systems could be accommodated by shrinking the flags > field to 16 bits (the atomic_t variant is currently unused) and by > providing only eight bits for CPU on such systems. > > It is not clear that the addition of the fields to __call_single_node > are really needed. > > Link: https://lore.kernel.org/lkml/20200615164048.GC2531@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Cc: Frederic Weisbecker <frederic@xxxxxxxxxx> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > --- > include/linux/smp.h | 3 +++ > include/linux/smp_types.h | 3 +++ > kernel/smp.c | 2 ++ > 3 files changed, 8 insertions(+) > > diff --git a/include/linux/smp.h b/include/linux/smp.h > index 80d557e..9f13966 100644 > --- a/include/linux/smp.h > +++ b/include/linux/smp.h > @@ -26,6 +26,9 @@ struct __call_single_data { > struct { > struct llist_node llist; > unsigned int flags; > +#ifdef CONFIG_64BIT > + u16 src, dst; > +#endif > }; > }; > smp_call_func_t func; > diff --git a/include/linux/smp_types.h b/include/linux/smp_types.h > index 364b3ae..2e8461a 100644 > --- a/include/linux/smp_types.h > +++ b/include/linux/smp_types.h > @@ -61,6 +61,9 @@ struct __call_single_node { > unsigned int u_flags; > atomic_t a_flags; > }; > +#ifdef CONFIG_64BIT > + u16 src, dst; > +#endif > }; > > #endif /* __LINUX_SMP_TYPES_H */ > diff --git a/kernel/smp.c b/kernel/smp.c > index d0ae8eb..a47382d 100644 > --- a/kernel/smp.c > +++ b/kernel/smp.c > @@ -375,6 +375,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info, > > csd->func = func; > csd->info = info; > + csd->dst = cpu; Would this and the next modification cause compile errors with CONFIG_64BIT = n? I saw you add #ifdef guard in the next patch, so maybe move those two into next patch (of course, if they trigger compile errors) Regards, Boqun > > err = generic_exec_single(cpu, csd); > > @@ -540,6 +541,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask, > csd->flags |= CSD_TYPE_SYNC; > csd->func = func; > csd->info = info; > + csd->dst = cpu; > if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) > __cpumask_set_cpu(cpu, cfd->cpumask_ipi); > } > -- > 2.9.5 >
